Abstract: [Object] To significantly increased the convenience in suctioning dust on a mop with use of a negative pressure of an electric vacuum cleaner. [Solution] A hose coupling device 10 includes a connecting pipe 14, a branch pipe 15, a ball valve 40. The connecting pipe 14 has openings, one of the openings configured as a first inlet 31 and another one of the openings configured as an outlet 33 communicating with the one of the openings. The branch pipe 15 continues from a lateral surface of the connecting pipe 14 and has an opening configured as a second inlet 32. The ball valve 40 is arranged in a valve box 35 at which the connecting pipe 14 and the branch pipe 15 communicate such that the ball valve 40 is rotatable about a rotation axis corresponding to an axis of the branch pipe 15 while the ball valve 40 remains in contact with an inner wall of the valve box 35.